linux.git/drivers/tty/serial, branch v5.10.247

serial: amba-pl011: prefer dma_mapping_error() over explicit address checking

2025-12-06T21:08:23+00:00

commit eb4917f557d43c7a1c805dd73ffcdfddb2aba39a upstream.

Check for returned DMA addresses using specialized dma_mapping_error()
helper which is generally recommended for this purpose by
Documentation/core-api/dma-api.rst:

  "In some circumstances dma_map_single(), ...
will fail to create a mapping. A driver can check for these errors
by testing the returned DMA address with dma_mapping_error()."

Found via static analysis and this is similar to commit fa0308134d26
("ALSA: memalloc: prefer dma_mapping_error() over explicit address checking")

Fixes: 58ac1b379979 ("ARM: PL011: Fix DMA support")
Cc: stable 
Signed-off-by: Miaoqian Lin 
Reviewed-by: Gregory CLEMENT 
Link: https://patch.msgid.link/20251027092053.87937-1-linmq006@gmail.com
Signed-off-by: Greg Kroah-Hartman

serial: 8250_dw: handle reset control deassert error

2025-12-06T21:08:08+00:00

[ Upstream commit daeb4037adf7d3349b4a1fb792f4bc9824686a4b ]

Check the return value of reset_control_deassert() in the probe
function to prevent continuing probe when reset deassertion fails.

Previously, reset_control_deassert() was called without checking its
return value, which could lead to probe continuing even when the
device reset wasn't properly deasserted.

The fix checks the return value and returns an error with dev_err_probe()
if reset deassertion fails, providing better error handling and
diagnostics.

Fixes: acbdad8dd1ab ("serial: 8250_dw: simplify optional reset handling")
Cc: stable 
Signed-off-by: Artem Shimko 
Link: https://patch.msgid.link/20251019095131.252848-1-a.shimko.dev@gmail.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

serial: 8250_dw: Use devm_add_action_or_reset()

2025-12-06T21:08:08+00:00

[ Upstream commit 295b09128d12fb1a7a67f771cc0ae0df869eafaf ]

Slightly simplify ->probe() and drop a few goto labels by using
devm_add_action_or_reset() for clock and reset cleanup.

Signed-off-by: Andy Shevchenko 
Link: https://lore.kernel.org/r/20220509172129.37770-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman 
Stable-dep-of: daeb4037adf7 ("serial: 8250_dw: handle reset control deassert error")
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

serial: 8250_exar: add support for Advantech 2 port card with Device ID 0x0018

2025-10-29T13:01:23+00:00

commit e7cbce761fe3fcbcb49bcf30d4f8ca5e1a9ee2a0 upstream.

The Advantech 2-port serial card with PCI vendor=0x13fe and device=0x0018
has a 'XR17V35X' chip installed on the circuit board. Therefore, this
driver can be used instead of theu outdated out-of-tree driver from the
manufacturer.

Signed-off-by: Florian Eckert 
Cc: stable 
Link: https://patch.msgid.link/20250924134115.2667650-1-fe@dev.tdt.de
Signed-off-by: Greg Kroah-Hartman

serial: max310x: Add error checking in probe()

2025-10-29T13:01:05+00:00

[ Upstream commit 672a37ba8af1f2ebcedeb94aea2cdd047f805f30 ]

Check if devm_i2c_new_dummy_device() fails.

Fixes: 2e1f2d9a9bdb ("serial: max310x: implement I2C support")
Signed-off-by: Dan Carpenter 
Link: https://lore.kernel.org/r/aJTMPZiKqeXSE-KM@stanley.mountain
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: stm32: allow selecting console when the driver is module

2025-10-29T13:01:02+00:00

commit cc4d900d0d6d8dd5c41832a93ff3cfa629a78f9a upstream.

Console can be enabled on the UART compile as module.
Change dependency to allow console mode when the driver is built as module.

Fixes: 48a6092fb41fa ("serial: stm32-usart: Add STM32 USART Driver")
Cc: stable@vger.kernel.org
Signed-off-by: Raphael Gallais-Pou 
Link: https://lore.kernel.org/r/20250822141923.61133-1-raphael.gallais-pou@foss.st.com
Signed-off-by: Greg Kroah-Hartman

serial: sc16is7xx: fix bug in flow control levels init

2025-10-02T11:35:42+00:00

[ Upstream commit 535fd4c98452c87537a40610abba45daf5761ec6 ]

When trying to set MCR[2], XON1 is incorrectly accessed instead. And when
writing to the TCR register to configure flow control levels, we are
incorrectly writing to the MSR register. The default value of $00 is then
used for TCR, which means that selectable trigger levels in FCR are used
in place of TCR.

TCR/TLR access requires EFR[4] (enable enhanced functions) and MCR[2]
to be set. EFR[4] is already set in probe().

MCR access requires LCR[7] to be zero.

Since LCR is set to $BF when trying to set MCR[2], XON1 is incorrectly
accessed instead because MCR shares the same address space as XON1.

Since MCR[2] is unmodified and still zero, when writing to TCR we are in
fact writing to MSR because TCR/TLR registers share the same address space
as MSR/SPR.

Fix by first removing useless reconfiguration of EFR[4] (enable enhanced
functions), as it is already enabled in sc16is7xx_probe() since commit
43c51bb573aa ("sc16is7xx: make sure device is in suspend once probed").
Now LCR is $00, which means that MCR access is enabled.

Also remove regcache_cache_bypass() calls since we no longer access the
enhanced registers set, and TCR is already declared as volatile (in fact
by declaring MSR as volatile, which shares the same address).

Finally disable access to TCR/TLR registers after modifying them by
clearing MCR[2].

Note: the comment about "... and internal clock div" is wrong and can be
      ignored/removed as access to internal clock div registers (DLL/DLH)
      is permitted only when LCR[7] is logic 1, not when enhanced features
      is enabled. And DLL/DLH access is not needed in sc16is7xx_startup().

Fixes: dfeae619d781 ("serial: sc16is7xx")
Cc: stable@vger.kernel.org
Signed-off-by: Hugo Villeneuve 
Link: https://lore.kernel.org/r/20250731124451.1108864-1-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman 
[ changed regmap variable from one->regmap to s->regmap ]
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

serial: 8250: fix panic due to PSLVERR

2025-08-28T14:22:48+00:00

commit 7f8fdd4dbffc05982b96caf586f77a014b2a9353 upstream.

When the PSLVERR_RESP_EN parameter is set to 1, the device generates
an error response if an attempt is made to read an empty RBR (Receive
Buffer Register) while the FIFO is enabled.

In serial8250_do_startup(), calling serial_port_out(port, UART_LCR,
UART_LCR_WLEN8) triggers dw8250_check_lcr(), which invokes
dw8250_force_idle() and serial8250_clear_and_reinit_fifos(). The latter
function enables the FIFO via serial_out(p, UART_FCR, p->fcr).
Execution proceeds to the serial_port_in(port, UART_RX).
This satisfies the PSLVERR trigger condition.

When another CPU (e.g., using printk()) is accessing the UART (UART
is busy), the current CPU fails the check (value & ~UART_LCR_SPAR) ==
(lcr & ~UART_LCR_SPAR) in dw8250_check_lcr(), causing it to enter
dw8250_force_idle().

Put serial_port_out(port, UART_LCR, UART_LCR_WLEN8) under the port->lock
to fix this issue.

Panic backtrace:
[    0.442336] Oops - unknown exception [#1]
[    0.442343] epc : dw8250_serial_in32+0x1e/0x4a
[    0.442351]  ra : serial8250_do_startup+0x2c8/0x88e
...
[    0.442416] console_on_rootfs+0x26/0x70

Fixes: c49436b657d0 ("serial: 8250_dw: Improve unwritable LCR workaround")
Link: https://lore.kernel.org/all/84cydt5peu.fsf@jogness.linutronix.de/T/
Signed-off-by: Yunhui Cui 
Reviewed-by: John Ogness 
Cc: stable 
Link: https://lore.kernel.org/r/20250723023322.464-2-cuiyunhui@bytedance.com
[ Applied fix to serial8250_do_startup() instead of serial8250_initialize() ]
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

pch_uart: Fix dma_sync_sg_for_device() nents value

2025-08-28T14:22:27+00:00

commit 6c0e9f05c9d7875995b0e92ace71be947f280bbd upstream.

The dma_sync_sg_for_device() functions should be called with the same
nents as the dma_map_sg(), not the value the map function returned
according to the documentation in Documentation/core-api/dma-api.rst:450:
	With the sync_sg API, all the parameters must be the same
	as those passed into the sg mapping API.

Fixes: da3564ee027e ("pch_uart: add multi-scatter processing")
Cc: stable 
Signed-off-by: Thomas Fourier 
Reviewed-by: Andy Shevchenko 
Link: https://lore.kernel.org/r/20250701113452.18590-2-fourier.thomas@gmail.com
Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Increment the runtime usage counter for the earlycon device

2025-06-27T10:04:22+00:00

commit 651dee03696e1dfde6d9a7e8664bbdcd9a10ea7f upstream.

In the sh-sci driver, serial ports are mapped to the sci_ports[] array,
with earlycon mapped at index zero.

The uart_add_one_port() function eventually calls __device_attach(),
which, in turn, calls pm_request_idle(). The identified code path is as
follows:

uart_add_one_port() ->
  serial_ctrl_register_port() ->
    serial_core_register_port() ->
      serial_core_port_device_add() ->
        serial_base_port_add() ->
          device_add() ->
            bus_probe_device() ->
              device_initial_probe() ->
                __device_attach() ->
                  // ...
                  if (dev->p->dead) {
                    // ...
                  } else if (dev->driver) {
                    // ...
                  } else {
                    // ...
                    pm_request_idle(dev);
                    // ...
                  }

The earlycon device clocks are enabled by the bootloader. However, the
pm_request_idle() call in __device_attach() disables the SCI port clocks
while earlycon is still active.

The earlycon write function, serial_console_write(), calls
sci_poll_put_char() via serial_console_putchar(). If the SCI port clocks
are disabled, writing to earlycon may sometimes cause the SR.TDFE bit to
remain unset indefinitely, causing the while loop in sci_poll_put_char()
to never exit. On single-core SoCs, this can result in the system being
blocked during boot when this issue occurs.

To resolve this, increment the runtime PM usage counter for the earlycon
SCI device before registering the UART port.

Fixes: 0b0cced19ab1 ("serial: sh-sci: Add CONFIG_SERIAL_EARLYCON support")
Cc: stable@vger.kernel.org
Signed-off-by: Claudiu Beznea 
Link: https://lore.kernel.org/r/20250116182249.3828577-6-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman